Within months of "I Fought The Law" becoming a top 10 hit, Fuller was found dead in an automobile parked outside his Hollywood apartment. The Los Angeles deputy medical examiner, Jerry Nelson, performed the autopsy. According to Dean Kuipers:[7] "The report states that Bobby's face, chest, and side were covered in "petechial hemorrhages" probably caused by gasoline vapors and the summer heat. He found no bruises, no broken bones, no cuts. No evidence of beating." Kuipers further explains that boxes for "accident" and "suicide" were ticked, but next to the boxes were question marks. Despite the official cause of death, some commentators believe Fuller was murdered.[8][9]

Erik Greene, a relative of Sam Cooke, has cited similarities in the deaths of Cooke and Fuller. Fuller bandmate, Jim Reese, suspected that Charles Manson may have had something to do with Fuller's death but never provided credible evidence. A sensationalist crime website has speculated that the LAPD may have been involved because of Bobby's connection to a Mafia-related woman. [10]

After his brother's death, Randy Fuller took over lead vocal duties and named the band after himself, but the band broke up within months of Bobby's death. Randy Fuller recorded a couple of solo singles, then in spring 1969 joined Dewey Martin's New Buffalo (Springfield), which evolved into Blue Mountain Eagle in July 1969. He appeared on the band's lone LP for Atco Records in early 1970 before briefly joining Dewey Martin and Medicine Ball.